The study entails an analysis of forebrain mechanisms which enter into the normal performance of learned and spontaneous phonatory calls as well as jaw and tongue movement produced by rhesus monkeys. The program is designed to reveal how anterior cingulate gyrus and the motor face area of neocortex may participate in orofacial and phonatory control. The consequences of lesion damage to those structures will be assessed by determining acoustical and behavioral changes of calls given in an experimental situation. Concurrent use of lesioning and electrical stimulation will show whether spontaneous and elicited phonatory calls retain their normal characteristics and whether calls lost from the repertoire as a result of lesioning can be regained. This will also demonstrate influences on motor control. These measures help identify apraxic factors which might contribute to phonatory dysfunction. Analysis of single unit activity in face area and in anterior cingulate gyrus during orofacial movement and phonation will provide information to show the manner in which such neurons may participate in regulation of these activities. Comparisons with the very limited data from humans will help establish a view of the evolution of phonation mechanisms. The evidence from this work will yield information about a process which has not been adequately analyzed. The results may be applied in improving our knowledge of dysarthria and other mechanisms underlying phonatory disturbance in humans.